Butter preparation methods represent some of the oldest techniques for preserving fat components that are found in milk. Butter manufacture has been accomplished in one form or another for over 4500 years. Over the centuries, butter has been used for medicinal and cosmetic purposes, and as a human food.
Butter production techniques generally evolved into more sophisticated techniques as new forms and uses of equipment developed. For example, the barrel chum made its appearance toward the end of the 18th century when non-wooden manufacturing materials entered widespread use in creaming and butter-making equipment. These advances led to advances in cream separation techniques and, by 1879, continuous operation cream separators were known in parts of Europe. Likewise, butter production evolved from an individual farm activity to a factory-based technique with the introduction of milk pooling systems for creamery operation in the 1870s. Later advances in fat quantification techniques, pasteurization, refrigeration, and bacterial culture usage further advanced the art of butter production.
Butter is typically a minimum 80% fat, all butterfat, product. Butter is a water-in-oil emulsion made by an inversion process from cream, which is an oil-in-water emulsion. Butter remains a solid when refrigerated, but softens to a spreadable consistency after equilibration to room temperature. A stick of butter, for example, removed from a refrigerator can take about 30 to 45 minutes to equilibrate to room temperature. In fact, consumer practice is to leave the butter out for up to 2-hrs to soften it and use it for various applications. Butter melts to a thin liquid consistency at about 32-35° C. (90-95° F.).
Spreadable butters have been developed using a number of different techniques and compositions. These spreadable butters remain softer at colder temperatures and are therefore easier to use directly from refrigeration. In some cases, the spreadable butters are made by modifying the makeup of the butter's fat composition through chemical manipulation of the finished product. In other cases, vegetable oils are incorporated into the butter to obtain the softer characteristics. These, however, do not always have the desired performance attributes or taste characteristics compared to traditional butter. Butter products are also produced with altered characteristics by manipulating the cattle's feed but this has the drawback of being an expensive undertaking that has limited commercial use. Whipped butter has also been made that is more spreadable and is made through incorporation of nitrogen gas. The use of air for whipping can result in faster oxidation and development of rancidity in the butter.